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Status and prospects of the LHCb Experiment

Status and prospects of the LHCb Experiment. Neville Harnew University of Oxford. On behalf of the LHCb Collaboration. Beauty 2002, Santiago de Compostela 21st June 2002. The LHCb Collaboration (45+3 institutes). France: FR Annecy, Clermont-Ferrand, CPPM Marseille, LAL Orsay

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Status and prospects of the LHCb Experiment

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  1. Status and prospects of the LHCb Experiment Neville Harnew University of Oxford On behalf of the LHCb Collaboration Beauty 2002, Santiago de Compostela 21st June 2002

  2. The LHCb Collaboration (45+3 institutes) France:FR Annecy, Clermont-Ferrand, CPPM Marseille, LAL Orsay Germany:DE Tech. Univ. Dresden, Phys. Inst. Univ. Heidelberg, KIP Univ. Heidelberg, MPI Heidelberg, Italy:IT Bologna, Cagliari, Ferrara, Firenze, Frascati, Genoa, Milan, Univ. Rome I (La Sapienza), Univ. Rome II (Tor Vergata) Netherlands:NL NIKHEF Poland:PL Cracow Inst. Nucl. Phys. & Tech. Univ, Warsaw Soltan Inst. Spain:ES Univ. Barcelona, Univ. Santiago de Compostela Switzerland:CH Univ. Lausanne, Univ. Zürich UK:GB Univ. Bristol, Univ. Cambridge, Univ. Edinburgh, Univ. Glasgow, IC London, Univ. Liverpool, Univ. Oxford, RALCERN Brazil:BR UFRJ, CPBF China:CN IHEP(Beijing), Tsinghua Univ. Russia:RU BINP, INR, ITEP, IHEP, PNPI Romania:RO IFIN-HH (Bucharest) Ukraine:UA Inst. Phys. Tech. (Kharkov), Inst. Nucl. Research (Kiev) Technical Espoo-Vantaa Inst. Tech. (Finland), Geneva Engineering School (Switzerland)Associates: CEFET-RJ (Brazil)

  3. OUTLINE • Introduction • The LHCb experiment • Status of the experiment • Detector optimization • LHCb-light • Trigger strategy • Physics prospects • Measurement of angle g • Importance of high statistics • Summary and conclusions

  4. Unitarity Triangles Bd0  p+ p- Bd0  rp BS0  DS p Bd0  DK*0 BS0  DSK Bd0  D* p, 3p BS0  J/y f Bd0  J/yKS0 Physics motivation of LHCb • Standard Model • predicts large CP violating asymmetries for B mesons • CP violation predicted in many (often v.rare) decays • need large samples of Bd, Bu, Bs mesons, B baryons • Need consistency checks

  5. b |Vtd/Vts| |Vub/Vcb| a g b CP violation in 2007 • s(sin2b) ~ 0.02 (world average) • s(sin2a) ~ 0.1 • s( g ) ~ v.large ? • |Vtd/Vts| from DmS by CDF & D0 limited by theory • |Vub/Vcb| from b->u by BaBar & Belle

  6. LHC Luminosity • <L>LHCb = 2 x1032 cm-2 s-1 • bb = 500 b • sinelastic ~ 80 mb • 1012 bb / 107 s • (or 1 million per 10s) Advantage of LHC bb angular distribution

  7. LHCbExperiment (“classic”) • Acceptance • 10 – (250) 300 mrad (non) – bending plane • Particle ID • p-K separation 1<p<150 GeV/c • Vertexing • Proper time resolution • 43 fs Bs -> Dsp (K) • 30 fs Bs -> J/yf

  8. Status of construction & design • Experimental area • Magnet • VELO • RICH • Tracking system • Calorimeter • Muon system • Re-optimization of the detector

  9. Experimental area Head Wall Pillar Pit 8: DELPHI dismantling completed. Necessary modification work started. POINT 8 - UX85 March 2002

  10. Magnet • Warm magnet Al conductor • ∫B.dl ~ 4 Tm • All contracts placed and signed • Production well underway Bending of the Al conductor

  11. Si detectors ~1m VErtex LOcator • Si strip detectors, single sided, read-out 220 m thick, 1800 wedges. • Now 21 stations mounted inside the vacuum tank. ~200k readout channels. • Vertex detector crucial in ALL time-dependent CP violation studies.

  12. VELO test beam Test beam Reconstruction of Primary Vertex using 2d tracks sz~79 mm radialazimuth

  13. Aerogel C4F10 CF4 • 5 85 167 cm • 1.03 1.0014 1.0005 • 242 53 32 mrad • 0.6 2.6 4.4 GeV • 2.0 9.3 15.6 GeV RICH System • 2 RICH detectors • 3sp/K separation 3-80 GeV/c • 2sp/K separation 1-150 GeV/c

  14. C4F10 small rings Aerogel large rings CF4 Photon detection with HPDs -20 kV 1024 pixel prototype • Prototype 1024-pixel HPD (LHC speed) being developed • Major review end June 2002 • Backup MAPMT

  15. And in reality …

  16. RICH-2 Engineering Design • Assembly of Prototype window • 3-D CAD model

  17. Power of particle ID • Purity = 84% ; Efficiency = 90% • B p+p-

  18. LHCb Inner & Outer Tracking Inner tracker • Now full silicon soln. • Tests in progress Outer tracker • Straw tubes • 5mm diameter, occupancy <10% • 3m Prototype installed in HERA-B

  19. LHCb Calorimeters • ECAL – Shashlyk type (+ preshower) • 5952 cells • 25 X0 , 1.1l depth • sE/E = 0.10/sqrt(E) + 0.01 • Mass production started, ~30% modules produced. • HCAL – Tile calorimeter • 1468 cells • 5.6l • sE/E = 0.80/sqrt(E) + 0.1 • Module 0 built and tested • Mass production started

  20. Inner & outer region MWPC Outer region RPCs Rate < 1kHz/cm2 Muon system Muon system • 5 stations • 900 MWPCs • 480 RPC chambers • Production in preparation

  21. Detector optimization • LHCb material budget increased significantly since Technical Proposal. LHCb has been reoptimized. • Beampipe Al -> Be-Al alloy • possibility of first beampipe cone all Be • VELO reduced number of stations 25 -> 21 & thinner Si • Was 0.19 X0 (0.04 l0) ; Now 0.18 X0 • RICH-1 composite mirror and mirror support outside acceptance. • Was 0.14 X0, (0.05 l0) ; Now 0.085 X0 • Tracking stations from 9 -> 4 • Now 0.27 X0, (0.11 l0) ; Now 0.12 X0 • Trigger optimization : B-field to provide PT information. • New RICH-1 design required by presence of B-field.

  22. LHCb Light • No tracking stations in magnet region • “Vertical” RICH-1 • RESULT : an improved detector

  23. LHCb Light tracking • Reduce tracking stations:- • Track efficiency and ghost rates improved with fewer secondary interactions. B p+p- sample Preliminary conclusions

  24. pile-upvertex detector Muon System Calorimeter System 40 MHz high PT muons high PT electrons high PT hadrons high PTg / p0 pile-up veto 1 MHz Level-0 decision unit Level-1 trigger unit VELO 40 kHz (up to 100 kHz) Higher Levels All the detector LHCb trigger system Level-0 Level-1 Vertex trigger Levels-2&3

  25. B  p+ p- 0.1 TP L1 algorithm L1 with L0 info L1 with pT info 0.05 Minimum bias retention 0 0.2 0.4 0.6 0.8 1.0 Signal efficiency Optimized Level-1 trigger • Include Level-0 information • B  p+p- improved by factor 2 • Add pT information • Allow to work at low o/p rates (5-40) kHz • High signal efficiencies Work in progress :

  26. B-field in RICH-1 region • B field in VELO region • Si station TT1 has 10% of By • Momentum resolution using VELO tracks & TT1 • S(1/p)~0.2p + 0.01/GeV VELO RICH1

  27. Major re-design of RICH-1 • 2-mirror geometry • Magnetic shielding box • Retain Aerogel & C4F10

  28. LHCb Physics performance • Importance of redundancy • Importance of particle ID • Importance of BS modes • Importance of high statistics • Performance summary table Measurement of g Re-optimization of LHCb currently in progress. All performance figures are pre - detector optimization.

  29. ( ) Bs -> Ds K - +  Measurement of angle g (1) • Expect 2400 events in 1 year of data taking • s(g-2dg) = 60140 • Depends on(g-2dg) and strong phase diff. • 4 Rate asymmetries measure angleg-2dg • Theoretically clean

  30. Measurement of g (2) From Bd +- ,Bs K+K- • ACP = AdircosDmt + AmixsinDmt • ~5k events per year in each channel • Invoke U-spin symmetry & relate pp and KK coefficients to extract g • (Fleischer CERN-TH/2000-101) • s(g) ~ 5 – 10o [theory]

  31. ( ) Bd D*-+ ,D*+- Measures 2b+g 1 year 5 years s (2b + g) in degrees  Measurement of g (3) • 4 Time-dependent decay rates • Relies on efficient hadron trigger • CP asymmetry very small (need large statistics) - Inclusive D* reconstruction ~ 500 k events/year with S/B~5 - Add D*a1 channels ~ 360 k events/year - Get b from B->J/y Ks (2b + g) in degrees Assumes perfect knowledge (blue) and 10% uncertainty (red) in |h|

  32. Determination of g from the measurement of 6 time-integrated decay rates : Bd D0 K*0 ,Bd D0 K*0 , Bd D0CP=+1 K*0 Bd D0 K*0 ,Bd D0 K*0 , Bd D0CP=+1 K*0 Bd D0 K*0 signal K+p - K-p + K+K-, p+p- Measurement of g (4) From Bd0D0 K*0 Visible BR’s ~ 10-810-7 Measurement only possible with forward detector with particle ID LHCb sensitivity per year : s(g) ~ 10O

  33. B -> J/y Ks • sworld(sin 2b) ~ 0.02 by 2006 • What will LHCb bring to this topic ? • STATISTICS ! • sLHCb(sin 2b) ~ 0.02 in 1 year • True precision measurement of this parameter • Eg. Fit for direct CP-violating contribution

  34. LHCb performance • Performance figures are for: • 1 year’s running • Reconstructable events • Event yields are for tagged events • Performance figures are currently being re-evaluated. 45% Preliminary 64% 35%

  35. After 1 year of LHCb (2008)

  36. or maybe … • … maybe g will provide a surprise

  37. Summary • LHCb will perform a precision study of CP violation. A probe for physics beyond the SM. • Redundancy of measurements in many channels. Good particle ID, vertexing, and efficient & flexible trigger essential. • Detector construction has started and progressing well. Good balance of advanced and proven technologies. • LHCb will be ready for data-taking at LHC startup in 2007.

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